A review on multiscale computational studies for enhanced oil recovery using nanoparticles

Oil reservoirs around the globe are at their declining phase and in spite of enormous effectiveness of Enhanced Oil Recovery(EOR) in the Tertiary Stage. This process still bypasses some oil reason being surface forces responsible for holding oil inside the rock surface which are not being altered by the application of existing technologies. The processes coming under Tertiary Section Supplements primary and secondary sections. However, the mechanism of operating is different in both. Nanoparticles are showing a significant role in EOR techniques and is a promising approach to increase crude oil extraction. This is due to the fact that size of nanoparticles used for EOR lies in the range of 1-100 nm. It is also an interesting fact that in different operational conditions and parameters, the performance of nanoparticles also vary and some are more effective than others, which leads to various levels of recovery in the EOR process. In the present study, we intend to summarize a report having an up to date status on nanotechnology assisted EOR mechanisms where nanoparticles are used as nano-catalysts, nano-emulsions and nanoparticles assisted EOR mechanisms to destabilize the oil layer on carbonate surface. This review also highlights the various mechanisms such Gibb's free energy, wettability alteration, and Interfacial Tension Reduction (ITR) including interaction of available nanoparticles with reservoirs. Experimental measurements for a wide range of nanoparticles are not only expensive but are challenging because of the relatively small size, especially for the measurements of thinner capillaries of a nanoscale diameter. Therefore, we considered computational simulations as a more adequate approach to gain more microscopic insights into the oil displacement process to classify the suitability of nanomaterials

Helicopter Augmented Control Laws for Ship Deck landing: HACLAS ONERA/DLR Joint Team

Different types of control laws are implemented, tested and compared for maritime operations particularly ship deck landing maneuvers at he flight simulation facilities at both DLR (German Aerospace Center) and ONERA (The French Aerospace Lab). At DLR, ”classical” cyclic and collective stick flight controls were used during the piloted simulator trials while active side-sticks were operated at ONERA. A joint maritime scenario for ship deck landing in the simulation environments of both institutes is presented. Test methodologies and assessment techniques to evaluate the ship deck landings are harmonized based on different criteria such as quantitative measures and handling qualities (HQ) ratings in order to analyze the developed control laws. Simulation results based on pilot studies for an EC135 in the DLR simulator and an EC225 at ONERA are presented

Evaluation of a Head-Mounted Display and Advanced Flight Control Laws for Helicopter Ship Deck Landing

Within the maritime environment, helicopters can be used for a wide variety of missions including rescue missions, transport of personnel and material as well as for surveillance and reconnaissance. To perform such tasks on open sea and to expand the onshore refueling range, ship deck landings are necessary. Adverse weather conditions, such as high winds, fog and precipitation lead to strong ship movements and create a turbulent environment on the ship's landing deck. Combined with few visual cues, ship deck operations put a high workload on pilots which can compromise flight safety. To support pilots during ship deck operations a symbology concept was integrated into the previously developed head-mounted display (HMD) based on a Microsoft HoloLens 2. Three advanced flight control modes were developed for the approach phase. Results from a simulator campaign with pilots in a realistic scenario indicate that the handling qualities can degrade with the HMD and only the relative translational rate command (RTRC) is suited as advanced control mode for ship deck operation

High-Fidelity Modeling and Control Design for a Cooperative High Altitude Long Endurance Aircraft Landing System

High Altitude Long Endurance (HALE) aircraft can take flight to altitudes as high as 20 km and can stay there for long periods of time. In this article, the viability of landing such an aircraft on a mobile platform using a cooperative control strategy for motion synchronization is examined. Time domain system identification is applied to create a model of the Elektra 2 Solar HALE aircraft, which was found to be high fidelity by the Federal Aviation Administration (FAA) standards. An analysis is made to evaluate the feasibility of autonomously landing the HALE Unmanned Aerial Vehicle (UAV) on top of a ground vehicle with a roof-mounted landing platform. Controller synthesis is done for the individual vehicles as well as the cooperative landing control, leading to an examination of the overall system stability and performance, using both deterministic and stochastic methods

Neurodevelopmental disorders in children aged 2-9 years: Population-based burden estimates across five regions in India.

BACKGROUND: Neurodevelopmental disorders (NDDs) compromise the development and attainment of full social and economic potential at individual, family, community, and country levels. Paucity of data on NDDs slows down policy and programmatic action in most developing countries despite perceived high burden. METHODS AND FINDINGS: We assessed 3,964 children (with almost equal number of boys and girls distributed in 2-<6 and 6-9 year age categories) identified from five geographically diverse populations in India using cluster sampling technique (probability proportionate to population size). These were from the North-Central, i.e., Palwal (N = 998; all rural, 16.4% non-Hindu, 25.3% from scheduled caste/tribe [SC-ST] [these are considered underserved communities who are eligible for affirmative action]); North, i.e., Kangra (N = 997; 91.6% rural, 3.7% non-Hindu, 25.3% SC-ST); East, i.e., Dhenkanal (N = 981; 89.8% rural, 1.2% non-Hindu, 38.0% SC-ST); South, i.e., Hyderabad (N = 495; all urban, 25.7% non-Hindu, 27.3% SC-ST) and West, i.e., North Goa (N = 493; 68.0% rural, 11.4% non-Hindu, 18.5% SC-ST). All children were assessed for vision impairment (VI), epilepsy (Epi), neuromotor impairments including cerebral palsy (NMI-CP), hearing impairment (HI), speech and language disorders, autism spectrum disorders (ASDs), and intellectual disability (ID). Furthermore, 6-9-year-old children were also assessed for attention deficit hyperactivity disorder (ADHD) and learning disorders (LDs). We standardized sample characteristics as per Census of India 2011 to arrive at district level and all-sites-pooled estimates. Site-specific prevalence of any of seven NDDs in 2-<6 year olds ranged from 2.9% (95% CI 1.6-5.5) to 18.7% (95% CI 14.7-23.6), and for any of nine NDDs in the 6-9-year-old children, from 6.5% (95% CI 4.6-9.1) to 18.5% (95% CI 15.3-22.3). Two or more NDDs were present in 0.4% (95% CI 0.1-1.7) to 4.3% (95% CI 2.2-8.2) in the younger age category and 0.7% (95% CI 0.2-2.0) to 5.3% (95% CI 3.3-8.2) in the older age category. All-site-pooled estimates for NDDs were 9.2% (95% CI 7.5-11.2) and 13.6% (95% CI 11.3-16.2) in children of 2-<6 and 6-9 year age categories, respectively, without significant difference according to gender, rural/urban residence, or religion; almost one-fifth of these children had more than one NDD. The pooled estimates for prevalence increased by up to three percentage points when these were adjusted for national rates of stunting or low birth weight (LBW). HI, ID, speech and language disorders, Epi, and LDs were the common NDDs across sites. Upon risk modelling, noninstitutional delivery, history of perinatal asphyxia, neonatal illness, postnatal neurological/brain infections, stunting, LBW/prematurity, and older age category (6-9 year) were significantly associated with NDDs. The study sample was underrepresentative of stunting and LBW and had a 15.6% refusal. These factors could be contributing to underestimation of the true NDD burden in our population. CONCLUSIONS: The study identifies NDDs in children aged 2-9 years as a significant public health burden for India. HI was higher than and ASD prevalence comparable to the published global literature. Most risk factors of NDDs were modifiable and amenable to public health interventions

System Identification and Control Design for a Stratospheric Flight Mission of a Solar Electric Aircraft

A system identification approach is presented for Elektra Two Solar OPS, a high altitude long endurance (HALE) aircraft for stratospheric flight missions. A linear longitudinal model of the aircraft has been developed using a Two Step Method based system identification approach, which provides the biases in the states in the first step along with the force and moment parameters of a system in the second step unlike other common system identification approaches. In order to prove the credibility of the identified aircraft longitudinal model, the identified model has been validated using various methods including some statistical measures, a validation set from the flight test recorded data and a forward simulation to compute the states from the identified model. An optimization based controller tuning method has been presented based on a control design which was manually tuned in flight, using Ziegler-Nichols method which is not a reliable method for such stratospheric flight missions. The applicability of the designed controller has been verified using various methods. A frequency and time domain analysis has been performed to analyse the stability margins and compare other characteristics. A robustness analysis has been performed using Monte-Carlo simulations for a gust disturbance and the model parameter variations in order to validate the robust behaviour of the designed controller. Extensive simulation studies demonstrate that the proposed approach is capable of achieving a an acceptable model of the aircraft which is suitable to be used for the ultimate goal of autonomous stratospheric flight

An Overall Evaluation Toolchain for Assessing Helicopter Ship Deck Landings

An overall evaluation toolchain is implemented for assessing the helicopter ship deck landings. The toolchain evaluates various touchdown conditions like position, velocity and attitude errors between the ship deck and the helicopter. It also displays additional evaluation parameters for the entire approach. A preliminary pilot study was performed in a simulator within a complete maritime scenario design. The maritime simulation environment includes a nonlinear helicopter flight model with a model-based flight control system, a ship dynamic model with the simulated turbulent air wake and realistic wave and water effects. For a subjective assessment of the ship deck landings, qualitative pilot ratings using different rating scales were recorded during the pilot study. Simulation results show that the toolchain is well suited for assessing helicopter ship deck landing performance in a simulation environment

Evaluation of Helicopter Ship Deck Landing Control Laws in Piloted Simulations

This paper describes the development and implementation of newly designed helicopter ship deck landing control modes and their evaluation in a piloted simulation study. The ship deck landing modes are embedded in a model-following controller architecture. The employed control design is a complete model-following control system whichimposes the desired command model dynamics on the controlled helicopter. Different command types combined with various hold functions are implemented to make the task easier for the pilots. Three basic command types and three advanced command types, one without ship communication and two with ship ommunication, are implemented. A piloted simulation study was performed in a simulator to evaluate and compare the implemented control modes within a complete maritime scenario design. The evaluation of control modes is based on the success of helicopter ship deck landings which is assessed by a quantitative as well as a qualitative assessment. Simulation results demonstrate that the advanced command types improved the task performance as well as reduced the pilot workload extensively in comparison to the basic command types

Verbesserung der Flugsicherheit bei Hubschrauber-Schiffsdecklandungen

Aufgrund von schwierigen Wetterbedingungen mit hohen Windgeschwindigkeiten, schlechter Sicht und fehlenden visuellen Referenzen sowie den kleinen und hochdynamischen Landeplattformen gehören Schiffsdecklandungen zu den anspruchsvollsten Missionen für Hubschrauberpiloten. Im Rahmen der Projekte PiloDeck (Pilotenassistenz für Schiffsdecklandungen) und HEDELA (Helicopter Deck Landing Assistance) forscht das DLR Institut für Flugsystemtechnik an Technologien zur Reduzierung der Arbeitsbelastung und zur Verbesserung der Flugsicherheit bei Hubschrauber-Schiffsdecklandungen. Zur Verringerung der Arbeitsbelastung und zur Erhöhung des Situationsbewusstseins von Piloten im maritimen Umfeld wurde an zwei Pilotenassistenzsystemen geforscht. Es wurde ein Flugregler auf Basis eines relativen Translational Rate Command (TRC) zur Pilotenunterstützung im Endanflug bei hoher Turbulenz entwickelt. Weiterhin wurde ein kopfgetragenes Sichtsystem (Head-Mounted Display, HMD) mit einer maritimen Symbolik entwickelt und auf einer Microsoft HoloLens 2 realisiert. Das System wurde im Flugversuch über Land mit dem DLR Forschungshubschrauber ACT/FHS getestet. Im Forschungssimulator AVES (Air Vehicle Simulator) wurde zur Evaluation der Assistenzsysteme und zur Forschung an der notwendigen Simulationsgüte für Trainingssimulatoren eine umfangreiche maritime Simulationsumgebung aufgebaut. Diese beinhaltet die Modellierung der Umgebung mit Wellen- und Wettersimulationen, hochauflösende 3D-Modelle und ein Echtzeitbewegungsmodell für die Schiffsbewegung im Seegang sowie die Interaktion der turbulenten Strömung über dem Landedeck mit dem Hubschrauber. In diesem Vortrag werden die aktuellen wissenschaftlichen Ergebnisse aus pilotierten Simulatorkampagnen und realen Flugversuchen vorgestellt. Der Fokus liegt dabei auf den Erkenntnissen bezüglich der Bewertung der Assistenzsysteme sowie auf den Ergebnissen der Flugversuche mit dem visuellen Assistenzsystem

Evaluation of Pilot Assistance Systems for Helicopter Ship Deck Landing

The operation of helicopters on ships is one to most challenging tasks due to adverse weather conditions, the lack of visible cues, turbulent airwakes behind the ship and a moving confined landing spot on the ship. Currently, only a very limited number of pilot assistance systems are available to ease helicopter ship deck landings. The focus of this paper is the evaluation of a Head-Down Display (HDD), a Head-Mounted Display (HMD) and two different Attitude Command Attitude Hold (ACAH) flight control architectures for ship deck landings based on piloted simulation. A ship deck landing scenario at the research flight simulation facility Air Vehicle Simulator (AVES) has been extended to include turbulent ship airwakes from high-fidelity Computational Fluid Dynamics (CFD). The pilot assistance systems have been implemented at the simulator and evaluated by four helicopter pilots. In particular, the results show a favorable potential of the Head-Mounted Display and the flight control architectures